Slitting and routing machine

ABSTRACT

The invention contemplates a method and apparatus for producing a bore of prescribed size and shape in elongated stock which is to be or has been longitudinally cut into separate halves, the bore being completely and correctly defined by segments cut into both halves. The invention has particular application to pipe or conduit insulation, as a relatively hard foamed urethane or other plastic, wherein accurate fit and insulation-thickness uniformity are significant factors. In the forms described, the bore is made by a routing tool, which is driven on a rotary axis which is radial to the longitudinal axis of the stock or workpiece, the tool shank passing between slightly separated matching halves of the workpiece. Guide-blade means in the plane of the bit axis and of the work-piece axis assures accurate separation for the routing operation, and for unsevered stock the guide-blade means includes a cutting edge operative just prior to the routing operation.

United States Patent [1 1 Andrews et al.

1451 July 17,1973

[ SLITTING AND ROUTING MACHINE [75] Inventors: Theodore E. Andrews,Kutztown;

John J. Weller, Emmaus, both of Pa.

[73] Assignee: Armstrong Cork Company,

Lancaster, Pa.

22 Filed: Dec. 15, 1971 21 Appl. No.: 208,200

[52] US. Cl. 29/33 D, 29/33 R, 29/558, 83/9, 144/86, 90/11 C [51] Int.Cl B23p 23/02 [58] Field of Search 144/86; 90/11 C; 29/33 R, 33 D, 33 T,558; 83/9, 54, 924

[56] References Cited FOREIGN PATENTS OR APPLICATIONS 21,571 4/1930Netherlands 144/86 Primary Examiner-Francis S. l-lusar Attorney-NicholM. Sandoe et al.

[5 7 ABSTRACT The invention contemplates a method and apparatus forproducing a bore of prescribed size and shape in elongated stock whichis to be or has been longitudinally cut into separate halves, the borebeing completely and correctly defined by segments cut into both halves.The invention has particular application to pipe or conduit insulation,as a relatively hard foamed urethane or other plastic, wherein accuratefit and insulation-thickness uniformity are significant factors. In theforms described, the bore is made by a routing tool, which is driven ona rotary axis which is radial to the longitudinal axis of the stock orworkpiece, the tool shank passing between slightly separated matchinghalves of the workpiece. Guide-blade means in the plane of the bit axisand of the work-piece axis assures accurate separation for the routingoperation, and for unsevered stock the guide-blade means includes acutting edge operative just prior to the routing operation.

22 Claims, 7 Drawing Figures PATENIED JUL 1 7 I975 SHEET 2 0F 2 EZLEK 1SLITTING AND ROUTING MACHINE This invention relates to a method andmeans for producing a bore of prescribed size and shape in elongatedstock which is to be or has been longitudinally cut into separatehalves. The invention will be described in particular application to thedefinition of the bore in pipe insulation, as of relatively hard foamedplastic such as a cured urethane foam.

In Snelling US. Pat. No. 3,ll8,800, issued Jan. 21, 1964, there isdescribed a method and apparatus for producing continuous foamed plasticconduit. Such conduit is ideally suited for pipe insulation; inpractice, the continuous product is cut to standardized length, and isthen longitudinally severed into semi-cylindrical annular halves, foreach application to the pipe for which it has been designed. Suchtechniques call for large production of each particular size, becausethe conduit-producing machine must be shut down and completely re-set,in order to produce conduit of a different size. Further, when changingproduction from one size to another size, it is found that considerableproduct and material waste is generated before correct equilibriumconditions are established for the adequately concentric generation ofthe new-size conduit annulus.

It is, accordingly, an object of the invention to provide an improvedmethod and means of the character indicated.

Another object is to provide a method and means for the more economicalmanufacture of conduit of the character indicated.

A further object is to achieve the above objects while also producing asuperior product, in the sense of holding close tolerances as to borecontour and wall thickness.

It is also an object to provide a means of preparing a quality productof the character indicated, using, inter alia, the scrap or rejectproduct of prior techniques.

A specific object is to provide a method and means whereby bore contourcan be quickly selected, changed and cut from a given size of stockmaterial.

Another specific object is to produce conduit of the characterindicated, wherein a precision fit to standard pipe is inherentlyachievable, the fit being characterized by a direct interface betweenfoam pockets and the pipe itself, i.e., without any skin or otherintervening layer at the interface.

Other objects and various further features of novelty and invention willbe pointed out or will occur to those skilled in the art from a readingof the following specification, in conjunction with the accompanyingdrawings. In said drawings, which show, for illustrative purposes only,preferred forms of the invention:

FIG. 1 is a simplified view in perspective of a machine of theinvention, with certain parts broken away and in section, and with otherparts suggested by phantom outline, to reveal utmost overall detail ofthe cooperating parts;

FIG. 2 is an enlarged sectional view of one kind of stock material orworkpiece, for use in the machine of FIG. 1;

FIG. 3 is an enlarged sectional view taken substantially at the plane3--3 of FIG. 1, when the machine is operative upon the stock of FIG. 2;

FIG. 4 is a view similar to FIG. 2, after performing the operation ofthe machine of FIG. 1;

FIG. 5 is a view similar to FIG. 2, to show another kind of workpiecefor supply to the machine of FIG. 1;

FIG. 6 is a similar view, to illustrate production of a modified bore;and

FIG. 7 is a simplified and partly broken away, perspective view of amodified apparatus of the invention.

In FIG. 1 of the drawings, the invention is shown in application to amachine for slicing and boring stock or workpieces, exemplified by thesectional view of FIG. 2. Such stock may be of a variety of compositionsand shapes, and the bore contour may likewise be varied; however, forthe selected illustrative example, the workpiece (FIG. 2) iscylindrical, having been formed continuously along its central axis, andcut to standardized length for example, 3-inch diameter stock, cut to4-foot lengths. The stock shown comprises a circumferential wrap offlexible sheath material 10, such as suitably treated paper,polyethylene or other plastic sheet, a fabric, or a metal foil, or alaminate of some of these materials. The wrap 10 contains a solid foamedplastic body 11, such as a foamed urethane of relatively hard, stiff andlocally brittle character. The longitudinally extending edges of sheathl0 overlap at flap 12, of angular extent a, sheath 10 being bonded tobody 11 for the full circumferential extent, leaving flap l2 flexibleand free to be raised and bent backward, along a longitudinallyextending fold alignment at the limit (13) of bonding to body 11.

For the illustrative embodiment of FIG. I, a cylindrical bore,concentric with the cylindrical sheath 10, is to be formed in the body11, and for efficient performance as a thermal insulator, the resultingproduct must adhere to close tolerance requirements as to thicknessuniformity in the annular insulating wall. For ease of application ofthe insulator to a pipe or conduit to be insulated, the product is to beformed as matching semi-cylindrical havles.

In the machine of FIG. 1, the workpiece of FIG. 2 is introduced,endwise, into a fixed guide-bore system 15 for accurately guided supportas the workpiece is fed past a blade 16 having a sharp cutting edge 17which is oriented dimetrically through the guide axis, to sever theworkpiece into matching halves. A guide blade or wedge 18, inconjunction with a suitable tubular guide for the sheath l0, introducesa controlled angular separation of the sliced halves of the workpiece,so that a rotary cutter bit 19 (driven about a rotation axis which isradial and in the plane of blades 16-18) may generate the respectivecylindrically arcuate halves of the desired bore. A further blade 20,aligned with blades 16-18 and with the shank 21 of the cutter bit I9maintains workpiece stability throughout the process and until dischargeat the far right end of the guide system.

More specifically, the machine of FIG. I is built on a fixed bed orframe 22 which extends the length of the machine. At the inlet orslicing end, upstanding spaced brackets 23-24 rigidly position opposedsemicylindrical guide elements 25-26, sized for stabilized guidance ofthe particular sheath 10; for clarity of illustration, the guide element26 is merely suggested by phantom outline of its axial end, it beingunderstood to be an image match to the opposed guide element 25, andsuitable fastening is suggested at 25'. Elements 25-26 are outwardlyflanged at their longitudinally extending edges, being fastened at theirlower edges and being fixedly spaced by the amount A at their upperedges. An offset 27 secured to or forming part of the bracket 23establishes a firm reference for cantilevered support of blade 16 at itsupper end, such that the cutting edge 17 extends diametrically acrossthe section of guide bore 15, to a point just short of cutting the farside of the sheath l; cutting edge 17 is also preferably inclined asshown with respect to the longitudinal guide axis, for more effectiveslicing action on the body 11 and on the upper part of sheath 10,without destruction or loss of body material. In FIG. 2, the uprightaxis 28 denotes the plane of slicing action, being slightly angularlyoffset from the flap-fold axis 13; this orientation is achieved bypassing flap 12 through the gap A between upper flanges of guideelements 25-26, it being noted that a slot 29 for blade 16 is suitablyangularly offset from the adjacent upper flange 30 of element 25.

Longitudinally downstream from the entrance and slicing region, justdescribed, is a further system of spaced upright fixed brackets 31-32for positioning the bore-cutting and stabilizing elements 18-19-20.Continued guidance of the workpiece is provided by an elongatesemi-cylindrical trough 33 having an inner surface that is held smoothlycontinuous to that of elements 25-26; trough 33 may be fixed to theframe via connection at one end to brackets 31-32 and at the other endto a further bracket 34. A table 35 secured to brackets 31-32 above thealignment of guide bore rigidly mounts the guide blades 18-20 from aboveand, at the same time, it accommodates the mounting flange 36 for theelectric-motor-driven routing machine 37 for bit 19. To complete theidentification of parts, a suitable twisted guide-finger element 38 issecured to table 35, to intercept the flap 12 and to fold the samebackward along the fold axis 13, as suggested by the showing in FIG. 3.Finally, the support of the workpiece halves (in the routing region) iscompleted by cylindrically ar'cuate segments 39-40, carried by theoutward flanges of trough 33 along the longitudinal edges of the latter.

In operation, a workpiece (FIG. 2) is entered into the longitudinal endof the guide bore 15, with flap 12 folded at 13 and projecting radiallyoutward, through the gap A between upper guide flanges of elements25-26. Router 37 is running, in anticipation of the bore cut. Theworkpiece is pressed longitudinally inwardly, either manually, or by asuitable feed mechanism (not shown). In passing the edge 17, theworkpiece is longitudinally severed into matching halves, hingedlyconnected by the unsevered remote side of sheath 10. The thickness ofblade 16 imparts an initial'separation of the severed halves, about thehinged sheath connection, and the sharp or relatively narrow upstreamedge 41 of wedge 18 readily enters the separating gap. Preferably, thebody of blade 18 tapers inwardly in the radially inward direction andreaches a maximum thickness at its downstream end, at the maximum radiusof the workpiece; this maximum thickness is preferably selected toexceed the diameter of the bit shank 21, so that the shank 21 performsno work on the adjacent severed edges or faces of the workpiece. In thecourse of reaching the routing region, the flap 12 will have beensmoothly folded back, out of interference with routing action orbit-shank rotation. The bore contour is smoothly generated as long asthe workpiece is fed, the final cut of a given workpiece being achievedby feeding the next workpiece, or by longitudinally removing thefinished article at the discharge end. In the latter event, the secondstabilizing blade 20 provides assurance of bore-cutting alignment untilthe very end of the workpiece. It will be understood that the effectivediameter of the guide elements 33-39-40 is slightly enlarged from thatat 15, to allow for the wedge action at 18 and to pilot the severedhalves of the workpiece against the side faces of the wedge blade 18;FIG. 3 suggests that this relationship is adequate to enable the bitshank 21 to clear the separated halves of the workpiece.

As best seen in FIG. 3, the routing bit 19 comprises two likesemi-circular blades secured at diametrically opposed locations to theconically tapered end of the shank 21. The angle of taper exactlymatches the angular spread between separated halves of the workpiece.The nature of the foamed material 11 is such as to fragment andpulverize locally in the presence and path of the rapid blows struck bythe bit blades in the course of high-speed rotation, the surface ofrevolution of these blades being characterized by a cross-section whichis that of the circular bore halves 45-45 (FIG. 4), plus an angularoffset 8 (FIG. 3) which reflects the bit-shank diameter. Upon completionof the bore 45-45, the separated halves 11'-ll" of the workpiece can beabutted, as shown in FIG. 4, with flap 12 substantially overlappingsheath 10 beyond the plane (28) of the cut. And since accurate positioncontrol of the halves ll1l" and of the bit 19 is maintained at alltimes, the bore 45-45 can be held to close concentricity tolerances withrespect to sheath 10.

It should be observed that bit 19 is selected for generating a bore toaccurately fit a specified pipe diameter. For fit to a different pipesize, the same stock (FIG. 2) may be used, with an appropriate bit size.For example, the three-inch diameter stock initially mentioned inconnection with FIG. 2 can serve with equal effectiveness for thethermal insulation of standard l-inch, 34-inch and l-inch pipe sizes,merely by appropriate selection of bit size at 19, and otherwise usingprecisely the same machine of FIG. 1. It will be understood that themeans whereby router 37 is secured to table 35 may be of a quick-releasevariety, thus simplifying the process of bit change, as needed, and inFIG. 1 the numeral 46 will be understood to identify chucking means forremovably accommodating the replacement bit to router 37.

FIG. 5 is a sectional view to illustrate a modified type of stock,usable as the workpiece for the operations described in connection withFIG. 1. The stock of FIG. 5 comprises an elongated tube of foamedmaterial 50, having an external sheath 51 (as at 10 in FIG. 2) and aninternal sheath 52, as of paper. This stock may have been continuouslyformed as an annulus, by means of the character set forth in theabove-identified patent, and FIG. 5 illustrates that through somemaladjustment of the tube-forming mechanism, the inner wall 52 may notbe concentric with the outer wall 51; the stock of FIG. 5 may thus bereject material which was produced while attempting to form a tubularwall of uniform thickness. The stock of FIG. 5 may also have beenlongitudinally slitted into matching halves (50-50'), as shown, as bymeans of mechanism described in copending application Ser. No. 113,342,filed Feb. 8, 1971. But FIG. 5 illustrates that, regardless of theeccentric bore, and regardless of whether or not the workpiece hasalready been slitted into separable halves, it is not necessary tocondemn it to the scrap heap. The machine of FIG. 1 will gracefullyaccept its passage via the guide bore 15, using knife blade 16 to pilotthe already severed halves, and a properly selected bit 19 willconcentrically generate a new bore while disposing of the internalsheath 52; the phantom contours 53-53 suggest the routed bore halves,and the resulting product is just as able to meet concentricityspecifications as that already described for the solid workpiece of FIG.2. FIG. 4 is thus equally able to illustrate the product of the machineof FIG. 1, whether the initial workpiece is as shown in FIG. 2 or FIG.5.

Thus far, the descripiton has proceeded on the assumption that aconcentric bore is to be formed in cylindrical stock. It will beunderstood, however, that a deliberately eccentric bore can be providedby proper design and selection of bit 19, and by appropriate positioningof the same with respect to the guided central longitudinal axis of theworkpiece. Also, the bore may be of other shapes and contours, asillustrated by the square section generated by rotation of blades 55-56on the shank 57 in FIG. 6; again, it is noted that the angular offset 8(reflecting diameter of shank 57) separates the half-square bladeelements 55-56, to enable formation of a perfect-square bore sectioninthe workpiece. Still further, it will be understood that for externalor sheath contours other than circular (for example, a square externalperiphery), the machine of FIG. 1 need only be modified as necessary atthe guide bore (i.e., parts -26-33-39-40) to receive, locate, orient andsupport the extenral contour of the stock, in its longitudinal traversalof the slicing and routing stations of the machine.

It will be seen that the described invention achieves all statedobjects, enabling precision manufacture of insulation jackets or thelike, for a variety of internal and external contours. Economy isrealized through use of the same size basic stock to serve bores ofdifferent sizes, the only change necessary being substitution of the bit19, as appropriate. Further economy is realized through an ability touse workpieces previously regarded as reject or scrap material. Andwhatever the original nature of the workpiece, the final product ischaracterized by a skinless bore which is thus able to presentfoamed-material cavities directly at the interface with the pipe orconduit to which it is fitted.

While the invention has been described in detail for the preferred formshown, it will be understood that modifications may be made withoutdeparature from the invetion. For example, the elongation axis of theguide bore 15 may be oriented vertically, the inlet being at the upperend, so as to facilitate gravity-feed of plural workpieces in anelongate inlet 15, and at the same time to provide a natural gravitydischarge for the pulverized offal which results from routing action.

Still further, the machine may have means for the longitudinally fixedretention of the workpiece, during a longitduinally guided traverse ofthe work by the routing longitudinally and its associated guide blades;such an embodiment is illustrated in FIG. 7, wherein an elongatesemi-cylindrical trough 60 is supported on a horizontal axis, betweenbase elements or feet 61-62. The trough 60 is selected for lengthsubstantially exceeding the length of the workpiece, and for curvatureappropriate to support and stabilize the sheath 10 of the workpiece.Stop means such as a lug 63 fixed in trough 60, and substantially shortof the end of trough 60, provides axial retention of the workpieceduring a working traverse of a tool slide 64, from right to left, in thesense of FIG. 7. Slide 64 is shown as cylindrically arcuate, ofcurvature appropriate to the accommodation of separate halves of theworkpiece, the longitudinal edges being shaped for guidance and supportin suitable channels 65 in the corresponding edges of trough 60. Frontand back stabilizing blades 66-67, in the same upstanding plane, are onopposite sides of the router bit 68 and its shank 69, and a handle 70 onthe router motor housing 71 provides a convenient means of manuallypropelling the slide 64 for a working traverse of the workpiece. If theworkpiece has already been sliced into matching elongatesemi-cylindrical halves, as in FIG. 5, then the front blade 66 performsmerely the wedging action discussed above for blade 18, it beingunderstood that flap-guide means (similar to guide element 38) isprovided on slide 64 to fold the workpiece flap 12 out of the path ofthe router bit and its shank. If on the other hand, the stock has notbeen sliced, then blade 66 may be of greater cantilevered extent, assuggested by phantom outline 66', and with a forward knife or sliceredge 66", as discussed at 17 in the case of blade 16; of course, thework-positioning lug means 63 should be angularly offset from the pathof blade 66-66' and router bit 68, so as to allow full passage of thebit 68 through the work, without sacrifice of guided support for slide64. The tool of FIG. 7 will be seen as convenient for field use, whereinbasic uncut stock of the same external diameter is to be bored to fit avariety of different pipe sizes needed as a given pipe installation isbeing made, the only change necessary being hit substitution in thechuck of the tool 71.

Throughout this specification, the use of a router and of a spade-typebit has of course covered the preferred technique of generating thedesired bore contour in the work. The use of this terminology will,however, additionally be understood to be broadly descriptive to othertypes of cutting devices, as may be appropriate to generate the borecontour in various kinds of body material 11. For exmaple, vibratorytool elements, such as ultrasonically driven elements, may be preferredif the body material 11 is sufficiently brittle to pulverize ontool-element impact. The principal point is that the bore-cutting toolis radially positioned in the gap between longitudinally severedworkpiece halves, and the effective cutting profile of the tool elementmatches the desired bore, plus the angular or radial ofl'set apropriateto the effective width of the bit shank or of such other element orelements 18-33-39-40 as may determine work-half separation.

What is claimed is:

1. Apparatus for forming a characterized bore in an elongated workpieceof substantially constant crosssection comprising a frame includingelongated workpiece support means for establishing a fixed orientationof the elongation axis of the workpiece, and tooling carried by saidframe and including router means and blade means including a knife edge,said blade means and router means being symmetrically supported withrespect to a single radial plane which includes a generally centralelongated axis of the workpiece support means, said knife edge beingforward of said router means, whereby a workpiece may be at leastpartially severed without substantial removal of workpiece material,said router means including a shank driven in rotation on an axisextending generally radially in said plane and generating a cuttingsurface of revolution having a cross-section of the desiredcharacterizedbore section plus a radial offset at least as great as theshank radius, said blade means having a maximum thickness substantiallyequal to the shank diameter, and said frame including means for theguided longitudinal traverse of the workpiece and of said tooling withrespect to each other.

2. Apparatus according to claim 1, in which said tooling is relativelyfixed and said last-defined means includes an elongated workpiece guideforming part of said support means.

3. Apparatus for forming a characterized bore in an elongated workpieceof substantially constant crosssection, comprising a frame includingelongated workpiece support means for establishing a fixed orientationof the elongation axis of the workpiece, and tooling carried by saidframe and including balde means and router means symmetrically supportedwith respect to a single radial plane which includes a generally centralelongated axis of the workpiece support means, said router meansincluding a shank driven in rotation on an axis extending generallyradially in said plane ang generating a cutting surface of revolutionhaving a crosssection of the desired characterized-bore section plus aradial offset at least as great as the shank radius, said blade meanshaving a maximum thickness substantially equal to the shank diameter,and said frame including an elongated guide and said tooling including aslide movable along said guide for the guided longitudinal traverse ofthe workpiece and of said tooling with respect to each other.

4. Apparatus for forming a characterized bore in an elongated workpieceof substantially constant crosssection, comprising a frame includingelongated workpiece support means for establishing a fixed orientationof the elongation axis of the workpiece, and tooling carried by saidframe and including blade means and router means symmetrically supportedwith respect to a single radial plane which includes a generally centralelongated axis of the workpiece support means, said router meansincluding a shank driven in rotation on an axis extending generallyradially in said plane and generating a cutting surface of revolutionhaving a crosssection of the desired characterized-bore section plus aradial offset at least as great as the shank radius, said blade meansbeing of wedge-shaped varying thickness having a maximum thicknesssubstantially equal to the shank diameter, said blade means having arelatively thin leading-edge portion longitudinally more remote fromsaid routing means than said maximum-thickness portion, and said frameincluding means for the guided longitudinal traverse of the workpieceand of said tooling with respect to each other.

5. Apparatus according to claim 1, in which said blade means comprisesblade elements aligned with each other and with the rotary axis of saidrouting means and on opposite longitudinal sides of said routing means.

6. Apparatus according to claim 1, in which said cutting edge extendssubstantially fully across the workpiece-supporting region of theworkpiece support means.

7. Apparatus according to claim 1, in which said cutting edge is alsoinclined to said elongation axis.

8. Apparatus for forming a characterized bore in an elongated workpiecehaving a cylindrical outer surface, comprising a frame including aconcave cylindrical support conforming to and for guiding the workpieceby its cylindrical outer surface, knife means carried with said supportand including a cutting edge extending substantially diametricallyacross the concave support for at least partially separating into twomatching halves an elongated workpiece fed into said support and in thedirection toward said cutting edge, whereby the separation may beachieved substantially without loss of workpiece material, and a routingtool carried by said frame and including a bit shank on a rotary axiswhich extends radially of the support axis in general alignment with theradial plane which includes the cutting edge and at a locationdownstream from the cutting edge, whereby the two halves may beseparated at least to an extent permitting tool-shank passage betweenknife-cut adjacent surfaces of said halves, said too] including acutting element which generates a surface of revolution having across-section matching that of the characterized bore at a radial offsetwhich is at least substantially one-half such separation of theworkpiece parts.

9. Apparatus according to claim 8, for operation on a workpiece having arelatively thin flexible peripheral sheath, said knife means having acantilevered-support relation with said frame and said cutting edegeextending diametrically to a location short of severing thediametrically remote part of said sheath, whereby the sheath hingedlyretains otherwise severed halves of the workpiece.

10. Apparatus according to claim 8, in which said concave supportoverlaps the region of routing action and, at said region, is ofsufficiently larger effective diameter than that of an uncut workpieceas to allow separation of severed workpiece halves to at least theextent of permitting routing-shank passage between separated workpiecehalves.

ll. Apparatus according to claim 10, and including a guide blade carriedby said frame and projecting radially within the concave support inalignment with and proximate to the routing shank.

12. Apparatus according to claim 11, in which the effective maximumwidth of said guide blade is at least as great as the diameter of therouting shank.

13. Apparatus according to claim 1 l, in which the effective maximumwidth of said guide blade exceeds the diameter of the routing shank andis angularly symmetrically positioned with respect to the plane whichincludes the elongated axis and the rotary axis of the routing shank.

14. Apparatus according to claim 12, in which the extent of effectiveenlargement of the concave support at the region of routing action issubstantially matched to the effective maximum width of the guide blade,thereby assuring positive retention of separated workpiece halvesthroughout routing action.

15. Apparatus according to claim 11, in whcih said guide blade is one oftwo, said two blades being on opposite longitudinal sides of the rotaryaxis and in the plane of the rotary axis.

16. Apparatus according to claim 11, in which said guide blade ispositioned upstream from said routing shank and is of tapering thicknesswhich converges in the radially inward direction.

17. Apparatus according to claim 9, for operation on a workpiece inwhich the sheath is a circumferential wrap with a longitudinallyextending free flap in a region of circumferential overlap of thelongitudinal edges of the sheath, said support including flap-foldingguide means operative to fold the flap back over adjacent sheathmaterial, the angular location of the fold being adjacent to but offsetfrom said radial plane such that, for a workpiece oriented forflap-folding by said guide means, the workpiece is cut by said knifemeans in a region capable of later coverage by the flap when bent to itsoriginal circumferentially overlapping position.

18. Tthe method of forming a characterized bore in an elongatedworkpiece of substantially constant crosswith respect to said centralaxis and substantially in the slit plane and with said surface ofrevolution symmetrically positioned with respect to said central axis,and longitudinally traversing said tool and workpiece with respect toeach other.

19. The method of claim 18, for operation on a workpiece having aflexible peripheral sheath, the slitting extending to just short ofsevering the sheath, whereby the sheath serves as a hinged connection ofthe otherwise fully severed halves of the workpiece.

20. The method of claim 18, for operation on a workpiece of soliduniform section throughout, the slitting extending to at least themaximum effective radial extent of the rotary cutting tool.

21. The method of claim 18, for operation on a workpiece having anelongated bore of undesired contour and of cross-section less than thatof said surface of revolution, the slitting extending to at least theextent of severing the workpiece on one radial side of the bore.

22. The method of claim 18, for operation on a cylindrical workpiece,and wherein the rotary cutting tool is selected to generate a surface ofrevolution characterized by a half-section which is semicircular at saidoffset, the center of the semi-circle being positioned for I substantialcoincidence with the workpiece axis.

1. Apparatus for forming a characterized bore in an elongated workpieceof substantially constant cross-section comprising a frame includingelongated workpiece support means for establishing a fixed orientationof the elongation axis of the workpiece, and tooling carried by saidframe and including router means and blade means including a knife edge,said blade means and router means being symmetrically supported withrespect to a single radial plane which includes a generally centralelongated axis of the workpiece support means, said knife edge beingforward of said router means, whereby a workpiece may be at leastpartially severed without substantial removal of workpiece material,said router means including a shank driven in rotation on an axisextending generally radially in said plane and generating a cuttingsurface of revolution having a cross-section of the desiredcharacterized-bore section plus a radial offset at least as great as theshank radius, said blade means having a maximum thickness substantiallyequal to the shank diameter, and said frame including means for theguided longitudinal traverse of the workpiece and of said tooling withrespect to each other.
 2. Apparatus according to claim 1, in which saidtooling is relatively fixed and said last-defined means includes anelongated workpiece guide forming part of said support means. 2.Apparatus according to claim 1, in which said tooling is relativelyfixed and said last-defined means includes an elongated workpiece guideforming part of said support means.
 3. Apparatus for forming acharacterized bore in an elongated workpiece of substantially constantcross-section, comprising a frame including elongated workpiece supportmeans for establishing a fixed orientation of the elongation axis of theworkpiece, and tooling carried by said frame and including balde meansand router means symmetrically supported with respect to a single radialplane which includes a generally central elongated axis of the workpiecesupport means, said router means including a shank driven in rotation onan axis extending generally radially in said plane ang generating acutting surface of revolution having a cross-section of the desiredcharacterized-bore section plus a radial offset At least as great as theshank radius, said blade means having a maximum thickness substantiallyequal to the shank diameter, and said frame including an elongated guideand said tooling including a slide movable along said guide for theguided longitudinal traverse of the workpiece and of said tooling withrespect to each other.
 4. Apparatus for forming a characterized bore inan elongated workpiece of substantially constant cross-section,comprising a frame including elongated workpiece support means forestablishing a fixed orientation of the elongation axis of theworkpiece, and tooling carried by said frame and including blade meansand router means symmetrically supported with respect to a single radialplane which includes a generally central elongated axis of the workpiecesupport means, said router means including a shank driven in rotation onan axis extending generally radially in said plane and generating acutting surface of revolution having a cross-section of the desiredcharacterized-bore section plus a radial offset at least as great as theshank radius, said blade means being of wedge-shaped varying thicknesshaving a maximum thickness substantially equal to the shank diameter,said blade means having a relatively thin leading-edge portionlongitudinally more remote from said routing means than saidmaximum-thickness portion, and said frame including means for the guidedlongitudinal traverse of the workpiece and of said tooling with respectto each other.
 5. Apparatus according to claim 1, in which said blademeans comprises blade elements aligned with each other and with therotary axis of said routing means and on opposite longitudinal sides ofsaid routing means.
 6. Apparatus according to claim 1, in which saidcutting edge extends substantially fully across the workpiece-supportingregion of the workpiece support means.
 7. Apparatus according to claim1, in which said cutting edge is also inclined to said elongation axis.8. Apparatus for forming a characterized bore in an elongated workpiecehaving a cylindrical outer surface, comprising a frame including aconcave cylindrical support conforming to and for guiding the workpieceby its cylindrical outer surface, knife means carried with said supportand including a cutting edge extending substantially diametricallyacross the concave support for at least partially separating into twomatching halves an elongated workpiece fed into said support and in thedirection toward said cutting edge, whereby the separation may beachieved substantially without loss of workpiece material, and a routingtool carried by said frame and including a bit shank on a rotary axiswhich extends radially of the support axis in general alignment with theradial plane which includes the cutting edge and at a locationdownstream from the cutting edge, whereby the two halves may beseparated at least to an extent permitting tool-shank passage betweenknife-cut adjacent surfaces of said halves, said tool including acutting element which generates a surface of revolution having across-section matching that of the characterized bore at a radial offsetwhich is at least substantially one-half such separation of theworkpiece parts.
 9. Apparatus according to claim 8, for operation on aworkpiece having a relatively thin flexible peripheral sheath, saidknife means having a cantilevered-support relation with said frame andsaid cutting edege extending diametrically to a location short ofsevering the dia-metrically remote part of said sheath, whereby thesheath hingedly retains otherwise severed halves of the workpiece. 10.Apparatus according to claim 8, in which said concave support overlapsthe region of routing action and, at said region, is of sufficientlylarger effective diameter than that of an uncut workpiece as to allowseparation of severed workpiece halves to at least the extent ofpermitting routing-shank passage between separated workpiece halves. 11.Apparatus according to claim 10, and including a guide blade carried bysaid frame and projecting radially within the concave support inalignment with and proximate to the routing shank.
 12. Apparatusaccording to claim 11, in which the effective maximum width of saidguide blade is at least as great as the diameter of the routing shank.13. Apparatus according to claim 11, in which the effective maximumwidth of said guide blade exceeds the diameter of the routing shank andis angularly symmetrically positioned with respect to the plane whichincludes the elongated axis and the rotary axis of the routing shank.14. Apparatus according to claim 12, in which the extent of effectiveenlargement of the concave support at the region of routing action issubstantially matched to the effective maximum width of the guide blade,thereby assuring positive retention of separated workpiece halvesthroughout routing action.
 15. Apparatus according to claim 11, in whcihsaid guide blade is one of two, said two blades being on oppositelongitudinal sides of the rotary axis and in the plane of the rotaryaxis.
 16. Apparatus according to claim 11, in which said guide blade ispositioned upstream from said routing shank and is of tapering thicknesswhich converges in the radially inward direction.
 17. Apparatusaccording to claim 9, for operation on a workpiece in which the sheathis a circumferential wrap with a longitudinally extending free flap in aregion of circumferential overlap of the longitudinal edges of thesheath, said support including flap-folding guide means operative tofold the flap back over adjacent sheath material, the angular locationof the fold being adjacent to but offset from said radial plane suchthat, for a workpiece oriented for flap-folding by said guide means, theworkpiece is cut by said knife means in a region capable of latercoverage by the flap when bent to its original circumferentiallyoverlapping position.
 18. Tthe method of forming a characterized bore inan elongated workpiece of substantially constant cross-section, whichcomprises slitting the workpiece along a path which lies substantiallyin an elongated plane through a generally central axis of symmetry ofthe bore to be formed, thereby defining two at least partially separableparts of the workpiece, holding the workpiece parts in face-to-face atleast partially separated relation, selecting a rotary cutting toolwhich generates a surface of revolution of cross-section having thedesired bore-section characterization plus a radial offset equal to onehalf the separation of the workpiece parts, rotating said tool about anaxis which is radial with respect to said central axis and substantiallyin the slit plane and with said surface of revolution symmetricallypositioned with respect to said central axis, and longitudinallytraversing said tool and workpiece with respect to each other.
 19. Themethod of claim 18, for operation on a workpiece having a flexibleperipheral sheath, the slitting extending to just short of severing thesheath, whereby the sheath serves as a hinged connection of theotherwise fully severed halves of the workpiece.
 20. The method of claim18, for operation on a workpiece of solid uniform section throughout,the slitting extending to at least the maximum effective radial extentof the rotary cutting tool.
 21. The method of claim 18, for operation ona workpiece having an elongated bore of undesired contour and ofcross-section less than that of said surface of revolution, the slittingextending to at least the extent of severing the workpiece on one radialside of the bore.
 22. The method of claim 18, for operation on acylindrical workpiece, and wherein the rotary cutting tool is selectedto generate a surface of revolution characterized by a half-sectionwhich is semicircular at said offset, the center of the semi-circlebeing positioned for substantial coincidence with the workpiece axis.